Derivation of uncertainty budgets for continuous above-water radiometric measurements along an Atlantic Meridional Transect

Fiducial reference measurements are in-situ data traceable to metrology standards, with associated uncertainties. This paper presents the methodology used to derive the uncertainty budget for underway, above-water measurements from the Seabird Hyperspectral Surface Acquisition System deployed on an Atlantic Meridional Transect in 2018. The average uncertainty of remote sensing reflectance for clear sky days was ∼ 6% at wavelengths < 490 nm and ∼ 12% at wavelengths > 550 nm. The environmental variability such as sun position, wind speed and skylight distribution caused the greatest uncertainty. The different components of the uncertainty budget are critically assessed to indicate how the measurement procedure could be improved through reducing the principal uncertainty sources.